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SmartContract

o1js / Modules / SmartContract

Class: SmartContract

The main zkapp class. To write a zkapp, extend this class as such:

class YourSmartContract extends SmartContract {
  // your smart contract code here
}

Hierarchy​

Table of contents​

Constructors​

Properties​

Accessors​

Methods​

Constructors​

constructor​

• new SmartContract(address, tokenId?)

Parameters​

NameType
addressPublicKey
tokenId?Field

Overrides​

SmartContractBase.constructor

Defined in​

lib/zkapp.ts:574

Properties​

#_senderState​

• Private #_senderState: Object

Type declaration​

NameType
senderPublicKey
transactionIdnumber

Defined in​

lib/zkapp.ts:822

#executionState​

• Private #executionState: undefined | ExecutionState

Defined in​

lib/zkapp.ts:541

address​

• address: PublicKey

Defined in​

lib/zkapp.ts:538

events​

• events: Object = {}

A list of event types that can be emitted using this.emitEvent()`.

Index signature​

▪ [key: string]: FlexibleProvablePure\<any>

Defined in​

lib/zkapp.ts:928

tokenId​

• tokenId: Field

Defined in​

lib/zkapp.ts:539

_maxProofsVerified​

▪ Static Optional _maxProofsVerified: 0 | 2 | 1

Defined in​

lib/zkapp.ts:559

_methodMetadata​

▪ Static Optional _methodMetadata: Record\<string, { actions: number ; digest: string ; gates: Gate[] ; hasReturn: boolean ; rows: number }>

Defined in​

lib/zkapp.ts:548

_methods​

▪ Static Optional _methods: MethodInterface[]

Defined in​

lib/zkapp.ts:547

_provers​

▪ Static Optional _provers: Prover[]

Defined in​

lib/zkapp.ts:558

_verificationKey​

▪ Static Optional _verificationKey: Object

Type declaration​

NameType
datastring
hashField

Defined in​

lib/zkapp.ts:560

Accessors​

account​

• get account(): Account

Current account of the SmartContract.

Returns​

Account

Defined in​

lib/zkapp.ts:853

balance​

• get balance(): Object

Balance of this SmartContract.

Returns​

Object

NameType
addInPlace(x: string | number | bigint | UInt64 | UInt32 | Int64) => void
subInPlace(x: string | number | bigint | UInt64 | UInt32 | Int64) => void

Defined in​

lib/zkapp.ts:922

currentSlot​

• get currentSlot(): CurrentSlot

Current global slot on the network. This is the slot at which this transaction is included in a block. Since we cannot know this value at the time of transaction construction, this only has the assertBetween() method but no get() (impossible to implement) or assertEquals() (confusing, because the developer can't know the exact slot at which this will be included either)

Returns​

CurrentSlot

Defined in​

lib/zkapp.ts:867

network​

• get network(): Network

Current network state of the SmartContract.

Returns​

Network

Defined in​

lib/zkapp.ts:859

self​

• get self(): AccountUpdate

Returns the current AccountUpdate associated to this SmartContract.

Returns​

AccountUpdate

Defined in​

lib/zkapp.ts:779

sender​

• get sender(): PublicKey

The public key of the current transaction's sender account.

Throws an error if not inside a transaction, or the sender wasn't passed in.

Warning: The fact that this public key equals the current sender is not part of the proof. A malicious prover could use any other public key without affecting the validity of the proof.

Returns​

PublicKey

Defined in​

lib/zkapp.ts:832

token​

• get token(): Object

Returns​

Object

NameType
idField
parentTokenIdField
tokenOwnerPublicKey
burn(__namedParameters: { address: PublicKey | AccountUpdate | SmartContract ; amount: number | bigint | UInt64 }) => AccountUpdate
mint(__namedParameters: { address: PublicKey | AccountUpdate | SmartContract ; amount: number | bigint | UInt64 }) => AccountUpdate
send(__namedParameters: { amount: number | bigint | UInt64 ; from: PublicKey | AccountUpdate | SmartContract ; to: PublicKey | AccountUpdate | SmartContract }) => AccountUpdate

Deprecated

SmartContract.token will be removed, and token methods will only be available on TokenContract.internal. Instead of SmartContract.token.id, use TokenContract.deriveTokenId().

For security reasons, it is recommended to use TokenContract as the base contract for all tokens.

Defined in​

lib/zkapp.ts:877

tokenSymbol​

• get tokenSymbol(): Object

Returns​

Object

NameType
set(tokenSymbol: string) => void

Deprecated

use this.account.tokenSymbol

Defined in​

lib/zkapp.ts:916

Methods​

approve​

▸ approve(update): void

Approve an account update or tree / forest of updates. Doing this means you include the account update in the zkApp's public input, which allows you to read and use its content in a proof, make assertions about it, and modify it.

`@method` myApprovingMethod(update: AccountUpdate) {
  this.approve(update);

  // read balance on the account (for example)
  let balance = update.account.balance.getAndRequireEquals();
}

Under the hood, "approving" just means that the account update is made a child of the zkApp in the tree of account updates that forms the transaction. Similarly, if you pass in an AccountUpdateTree, the entire tree will become a subtree of the zkApp's account update.

Passing in a forest is a bit different, because it means you set the entire children of the zkApp's account update at once. approve() will fail if the zkApp's account update already has children, to prevent you from accidentally excluding important information from the public input.

Parameters​

NameType
updateAccountUpdate | AccountUpdateTree | AccountUpdateForest

Returns​

void

Defined in​

lib/zkapp.ts:902

deploy​

▸ deploy(«destructured»?): void

Deploys a SmartContract.

let tx = await Mina.transaction(sender, () => {
  AccountUpdate.fundNewAccount(sender);
  zkapp.deploy();
});
tx.sign([senderKey, zkAppKey]);

Parameters​

NameType
«destructured»Object
› verificationKey?Object
› verificationKey.datastring
› verificationKey.hashstring | Field
› zkappKey?PrivateKey

Returns​

void

Defined in​

lib/zkapp.ts:663

emitEvent​

▸ emitEvent\<K>(type, event): void

Emits an event. Events will be emitted as a part of the transaction and can be collected by archive nodes.

Type parameters​

NameType
Kextends string | number

Parameters​

NameType
typeK
eventany

Returns​

void

Defined in​

lib/zkapp.ts:934

fetchEvents​

▸ fetchEvents(start?, end?): Promise\<{ blockHash: string ; blockHeight: UInt32 ; chainStatus: string ; event: { data: ProvablePure\<any> ; transactionInfo: { transactionHash: string ; transactionMemo: string ; transactionStatus: string } } ; globalSlot: UInt32 ; parentBlockHash: string ; type: string }[]>

Asynchronously fetches events emitted by this SmartContract and returns an array of events with their corresponding types.

Parameters​

NameTypeDescription
start?UInt32The start height of the events to fetch.
end?UInt32The end height of the events to fetch. If not provided, fetches events up to the latest height.

Returns​

Promise\<{ blockHash: string ; blockHeight: UInt32 ; chainStatus: string ; event: { data: ProvablePure\<any> ; transactionInfo: { transactionHash: string ; transactionMemo: string ; transactionStatus: string } } ; globalSlot: UInt32 ; parentBlockHash: string ; type: string }[]>

A promise that resolves to an array of objects, each containing the event type and event data for the specified range.

Async

Throws

If there is an error fetching events from the Mina network.

Example

const startHeight = UInt32.from(1000);
const endHeight = UInt32.from(2000);
const events = await myZkapp.fetchEvents(startHeight, endHeight);
console.log(events);

Defined in​

lib/zkapp.ts:980

init​

▸ init(): void

SmartContract.init() will be called only when a SmartContract will be first deployed, not for redeployment. This method can be overridden as follows

class MyContract extends SmartContract {
 init() {
   super.init();
   this.account.permissions.set(...);
   this.x.set(Field(1));
 }
}

Returns​

void

Defined in​

lib/zkapp.ts:734

newSelf​

▸ newSelf(methodName?): AccountUpdate

Same as SmartContract.self but explicitly creates a new AccountUpdate.

Parameters​

NameType
methodName?string

Returns​

AccountUpdate

Defined in​

lib/zkapp.ts:814

requireSignature​

▸ requireSignature(): void

Use this command if the account update created by this SmartContract should be signed by the account owner, instead of authorized with a proof.

Note that the smart contract's Permissions determine which updates have to be (can be) authorized by a signature.

If you only want to avoid creating proofs for quicker testing, we advise you to use LocalBlockchain({ proofsEnabled: false }) instead of requireSignature(). Setting proofsEnabled to false allows you to test your transactions with the same authorization flow as in production, with the only difference being that quick mock proofs are filled in instead of real proofs.

Returns​

void

Defined in​

lib/zkapp.ts:755

send​

▸ send(args): AccountUpdate

Parameters​

NameType
argsObject
args.amountnumber | bigint | UInt64
args.toPublicKey | AccountUpdate | SmartContract

Returns​

AccountUpdate

Defined in​

lib/zkapp.ts:906

setPermissions​

▸ setPermissions(permissions): void

Parameters​

NameType
permissionsPermissions

Returns​

void

Deprecated

use this.account.permissions.set()

Defined in​

lib/zkapp.ts:1161

setValue​

▸ setValue\<T>(maybeValue, value): void

Type parameters​

Name
T

Parameters​

NameType
maybeValueSetOrKeep\<T>
valueT

Returns​

void

Deprecated

use this.account.<field>.set()

Defined in​

lib/zkapp.ts:1154

sign​

▸ sign(zkappKey?): void

Parameters​

NameType
zkappKey?PrivateKey

Returns​

void

Deprecated

this.sign() is deprecated in favor of this.requireSignature()

Defined in​

lib/zkapp.ts:761

skipAuthorization​

▸ skipAuthorization(): void

Use this command if the account update created by this SmartContract should have no authorization on it, instead of being authorized with a proof.

WARNING: This is a method that should rarely be useful. If you want to disable proofs for quicker testing, take a look at LocalBlockchain({ proofsEnabled: false }), which causes mock proofs to be created and doesn't require changing the authorization flow.

Returns​

void

Defined in​

lib/zkapp.ts:772

Proof​

▸ Static Proof(): typeof __class

Returns a Proof type that belongs to this SmartContract.

Returns​

typeof __class

Defined in​

lib/zkapp.ts:565

analyzeMethods​

▸ Static analyzeMethods(«destructured»?): Record\<string, { actions: number ; digest: string ; gates: Gate[] ; hasReturn: boolean ; rows: number }>

This function is run internally before compiling a smart contract, to collect metadata about what each of your smart contract methods does.

For external usage, this function can be handy because calling it involves running all methods in the same "mode" as compile() does, so it serves as a quick-to-run check for whether your contract can be compiled without errors, which can greatly speed up iterating.

analyzeMethods() will also return the number of rows of each of your method circuits (i.e., the number of constraints in the underlying proof system), which is a good indicator for circuit size and the time it will take to create proofs. To inspect the created circuit in detail, you can look at the returned gates.

Note: If this function was already called before, it will short-circuit and just return the metadata collected the first time.

Parameters​

NameType
«destructured»Object
› printSummaryundefined | boolean

Returns​

Record\<string, { actions: number ; digest: string ; gates: Gate[] ; hasReturn: boolean ; rows: number }>

an object, keyed by method name, each entry containing:

  • rows the size of the constraint system created by this method
  • digest a digest of the method circuit
  • hasReturn a boolean indicating whether the method returns a value
  • actions the number of actions the method dispatches
  • gates the constraint system, represented as an array of gates

Defined in​

lib/zkapp.ts:1100

compile​

▸ Static compile(«destructured»?): Promise\<{ provers: Prover[] ; verificationKey: { data: string ; hash: Field } ; verify: (statement: Statement\<FieldConst>, proof: unknown) => Promise\<boolean> }>

Compile your smart contract.

This generates both the prover functions, needed to create proofs for running @methods, and the verification key, needed to deploy your zkApp.

Although provers and verification key are returned by this method, they are also cached internally and used when needed, so you don't actually have to use the return value of this function.

Under the hood, "compiling" means calling into the lower-level Pickles and Kimchi libraries to create multiple prover & verifier indices (one for each smart contract method as part of a "step circuit" and one for the "wrap circuit" which recursively wraps it so that proofs end up in the original finite field). These are fairly expensive operations, so expect compiling to take at least 20 seconds, up to several minutes if your circuit is large or your hardware is not optimal for these operations.

Parameters​

NameType
«destructured»Object
› cacheundefined | Cache
› forceRecompileundefined | boolean

Returns​

Promise\<{ provers: Prover[] ; verificationKey: { data: string ; hash: Field } ; verify: (statement: Statement\<FieldConst>, proof: unknown) => Promise\<boolean> }>

Defined in​

lib/zkapp.ts:602

digest​

▸ Static digest(): string

Computes a hash of your smart contract, which will reliably change whenever one of your method circuits changes. This digest is quick to compute. it is designed to help with deciding whether a contract should be re-compiled or a cached verification key can be used.

Returns​

string

the digest, as a hex string

Defined in​

lib/zkapp.ts:643

runOutsideCircuit​

▸ Static runOutsideCircuit(run): void

Parameters​

NameType
run() => void

Returns​

void

Defined in​

lib/zkapp.ts:1074